1,3-Butadiene is a valuable hydrocarbon. Also known as buta-1,3-diene, erythrene, and vinylethylene, it is the simplest 1,3-diene compound. 1,3-Butadiene can be used as a monomer starting material for preparation of various polymers, including synthetic rubbers. 1,3-Butadiene can be used as a feedstock in the production of adiponitrile. 1,3-Butadiene can also be used as a substrate in certain Diels-Alder reactions.
1,3-Butadiene can be obtained from different sources, including dehydrogenation of n-butane and reaction of ethanol. 1,3-Butadiene can also be isolated from mixtures of C4 hydrocarbons, e.g., C4 fractions obtained from steam cracking processes. Crude 1,3-butadiene containing about 89% to about 99% 1,3-butadiene, by weight, and smaller quantities of 1,2-butadiene, 2-butenes (both cis and trans), propyne, and/or C5 hydrocarbons can be obtained from extractive distillation methods known in the art. Crude 1,3-butadiene can be further purified to provide 1,3-butadiene of 99.6% or greater purity, by weight.
Certain methods for purification of crude 1,3-butadiene can involve two-stage distillation through two separate distillation columns. In such methods, crude 1,3-butadiene containing propyne, 1,2-butadiene, and C5 hydrocarbons, as well as other compounds, can be fed into a first distillation column. Propyne can be removed as a gas (vapor) stream from the top of the first distillation column, while a liquid stream containing 1,3-butadiene, 1,2-butadiene, and C5 hydrocarbons is passed from the first distillation column into the second distillation column. 1,3-Butadiene can then be removed as a liquid stream from the top of the second distillation column, while 1,2-butadiene and C5 hydrocarbons are removed as a liquid stream from a lower portion of the column.
A drawback of certain methods for purification of crude 1,3-butadiene can be poor performance when the crude 1,3-butadiene contains significant quantities of cis- and/or trans-2-butene. There exists a need for processes and systems for purification of 1,3-butadiene to consistently high purity, even in the presence of relatively high levels of 2-butene.